Transcript
00:00:651Michele De Carli: Now, we are going to into the new, okay, into the new part.
00:14:360Michele De Carli: Oh, yeah, that's
00:24:290Michele De Carli: okay. So now we are
00:30:710Michele De Carli: So we had seen the how to calculate the loads
00:35:640Michele De Carli: right and the energy they or that much in their energy. But let's say that now
00:43:480Michele De Carli: you know that we, we have some some pick load. Okay, that you need to consider for sizing our system. Okay, now, as we have seen, basically, we have 3 types of heating and cooling system. One is, just based on water. Okay.
01:07:970Michele De Carli: there is another one which is
01:11:260Michele De Carli: a mix between air and water and another one with just the air. Okay, so before so then, it means that basically, we we have to consider that on one hand, we have to provide air into the building. Okay?
01:32:00Michele De Carli: And we see how we can do that. And on the other side. We need to heat the building, and that can be done
01:40:960Michele De Carli: same air or by means by means of water. Okay, which is heated on cooled.
01:49:120Michele De Carli: So, as I told you, it is better between
01:55:40Michele De Carli: we could start from the water, but from the hydraulic system, or or looking at the air. Okay, how to ventilate the buildings. I prefer to work or to
02:08:224Michele De Carli: explain or to see how we can manage the air into the building. Okay? Because if we do that.
02:16:920Michele De Carli: then it is easier also to talk about the the water or water in their base solution. Okay, so from from now, we start with the most, let's say, technical part. Okay, where we are going to see in the detail the technical issues. Okay, and the and the technical
02:41:430Michele De Carli: and the technologies available. And we will start with the air for the ventilation system.
02:49:340Michele De Carli: in order to start with a A with it. We will start with the easiest way to move the air inside of the of a building. Okay? So we are going to look at the so called
03:07:88Michele De Carli: controlled mechanical ventilation. Controlled mechanical ventilation is a solution. Okay, which is mainly used for residential building or small commercial applications. Okay, so
03:20:325Michele De Carli: the system that, for instance, we are right now here. Okay, which is here, where we can see we have the limits this side but
03:30:430Michele De Carli: in 3, 3 in 3 lines. Okay, let's say, basically, it is a more complicated system that we are going to see. Maybe so imagine that practically, as you will see.
03:44:900Michele De Carli: for small size, for small case solutions.
03:48:210Michele De Carli: We have basically Precalc, or, yes, pre calculated or pre selected
03:57:330Michele De Carli: to precise systems. Okay, so where we don't really need to make many calculations. Okay, so the calculations that we have to do when we consider this system are quite easy, okay to implement.
04:13:700Michele De Carli: But let's say, this is the the, let's say that this is the low entry level technology. Okay for regulation. But it is necessary. Okay, so we start with this solution, which is the basic and smallest and easiest solution. And then we are going to complicate a little bit. The the the topics. Okay? So we talk about this, which are suitable for residential applications. But
04:40:950Michele De Carli: I would like to remark that it is also not only for for small size, commercial application.
04:48:340Michele De Carli: Sorry not only for residential building, but no size. Commercial application.
04:54:845Michele De Carli: So
04:56:990Michele De Carli: why do we need ventilation? We have seen. Okay, when we talked about the Internet quality, we need to bring our air in order to to to
05:13:110Michele De Carli: or midway. Okay, the Ute. Sorry the pollutants in an in an environment.
05:22:919Michele De Carli: In the past we had a very poor very poor windows. Okay? Which could allow the air by infiltration, entering. Okay, entering the the buildings and the rooms. And at the same time also, the habit was upon a time we're different, because.
05:48:968Michele De Carli: there was always at least one person at all. Okay.
05:55:980Michele De Carli: And he's most of the of the of the families are playing.
06:01:460Michele De Carli: It was very common that wives didn't work, or they could be even the the grandfathers at home. Okay? And so basically, it was possible at that time to open windows in the morning to get air entering through the room.
06:20:890Michele De Carli: But today's this is a little bit different, because the windows are
06:26:600Michele De Carli: better performing. Okay, and also, they are tight. Okay, they are more tight. So there is less infiltration
06:36:80Michele De Carli: and and also less noise
06:39:820Michele De Carli: transmission. And basically, we live outside the house all day long.
06:47:340Michele De Carli: and we are not opening any more windows. And that becomes a problem. Because, I mean, we have problems, or we have seen that the potential pollutants that we have in a building. Okay.
07:03:760Michele De Carli: But besides that, we have to understand that, as I told you
07:10:917Michele De Carli: many times, the the the, the
07:16:460Michele De Carli: the worst pollutant that we have inside of a building are basically ourselves. So people, okay and people, they have 2 problems.
07:27:280Michele De Carli: They have several problems. But I mean, from our point of view, they have 2 problems. One is that they are emitting Co 2, okay, which is, as I told you, right. They're emitting bioafflerance, and we use Co. 2 as a marker for checking if their air quality is good or not.
07:44:350Michele De Carli: and we also emit the vapor, and, as we have seen, when we made the balance of vapor, we have seen that we have also some other vapor sources in the building which are related to the
08:00:70Michele De Carli: to hey!
08:04:530Michele De Carli: To clean out the building, to wash
08:08:940Michele De Carli: clothes, dry clothes, and so on the cooking. And so so let's say that in residential buildings the most effective parameter rather than I mean, if we are in an in an office building, then Co. 2 is a market.
08:25:480Michele De Carli: and and by by checking the level of Co. 2, we can see if we have proper or not regulation inside of the residential building. Since we have a lot of vapor production
08:41:700Michele De Carli: vapor is, let's say, the market.
08:45:540Michele De Carli: but also a pollutant. Okay? Because in 2
08:50:320Michele De Carli: in 2 humid places. Okay, there, might, we might have problems like more growth. Okay? And and also based on the the.
09:05:820Michele De Carli: let's say, okay, we might have problems. Okay, so let's say that it is physiological that we have paper production inside of a residential buildings. Okay, so it's normal normal.
09:24:880Michele De Carli: And we cannot avoid to have a vapor rate inside of building, especially in residential.
09:33:30Michele De Carli: but on the other side if we don't ventilate
09:38:910Michele De Carli: much as we have seen in one, in the, in, the, in the examples that we have seen, hey? In the, in the paper balance that we made last week. Okay?
09:50:610Michele De Carli: Then, we might have problems here. You see, this is a very interesting
09:58:680Michele De Carli: very interesting research activity which has been done in the beginning of 2,000. Okay, where they consider
10:07:520Michele De Carli: lots of lots of buildings. Okay, you have to imagine that at the least, each bar is more or less 100 dwellings. Okay? So it was a huge, extensive analysis. Okay? Based on more than 2,000 dwellings. Okay? And of course, they could select just the ones we which were.
10:27:140Michele De Carli: And when you, when you make this kind of of analysis of research, usually you have to reduce, then the number of of cases that you can analyze because of different issues and and problems. Okay, so in each of each of these bodies, at least 90. Okay, so so they started with more than 2,000 dwellings, and then they end up with a representative
10:55:569Michele De Carli: or or or or burnings number, with where they were sure to get this thing. Okay, you can see, this is the air change rate. Okay?
11:08:160Michele De Carli: And this is the relative risk of allergic symptoms. Okay, so what you can see is basically that if you reduce the ventilation because the lower the age rate, the lower the amount of ventilation, you can see that the relative risk of allergic symptoms increase.
11:28:420Michele De Carli: And you can see that basically the the meaning, the the function is minimized by, let's say.
11:34:270Michele De Carli: point 5. Okay, which is half the change rate, which is the usually recommended value for the the direction
11:46:190Michele De Carli: so relative risk of allergy increases, and
11:51:930Michele De Carli: especially what you get if you don't ventilate much as we have seen in the sample that I told you one week ago.
12:00:370Michele De Carli: we can get very high values of relative humidity.
12:05:350Michele De Carli: What is the problem of a a a, a too humid condition.
12:12:230Michele De Carli: Well,
12:15:940Michele De Carli: I won't go in detail on that, because that is part of the 1st semester course of managing buildings. Okay.
12:22:50Michele De Carli: but let's say that if locally so, if
12:26:370Michele De Carli: where you inner side or in the inner surface of your walls, okay, or it's awards. Yes, you are
12:40:710Michele De Carli: inside this area. Okay? Then you have a a probable
12:46:910Michele De Carli: mold growth. Okay, so this year happens because locally, you are, you have more than 80% of relative humidity. Okay, over
12:59:460Michele De Carli: the
13:01:240Michele De Carli: one month of moments. Okay? And when do you get inside this area when the relative humidity is high? Okay, just to show you imagine that we have
13:15:30Michele De Carli: like, imagine that we have 20 degrees of indoor air. Okay, this is 20 degrees and
13:24:500Michele De Carli: 50% of relative humidity. Okay.
13:27:860Michele De Carli: then, if you're here in order to enter in this line here, you need an internal
13:35:90Michele De Carli: temperature of the surface of about 11 degrees. Okay.
13:39:730Michele De Carli: which is, I mean, very low. Okay, so, but if you have, like 60 or 70, 70%, for instance, of relative humidity, okay, at 20 degrees. Then you can see that you reach this point at about
13:58:780Michele De Carli: 17.5 degrees. So
14:02:500Michele De Carli: where you have a a cold point on your wall, then you have more rooms.
14:08:630Michele De Carli: Okay? So this is what you might
14:11:330Michele De Carli: right? And in order to reduce this, you have to wait for it.
14:15:820Michele De Carli: Ventilation can be done only in a mechanical way. So it is well recognized and demonstrated by the literature that either you ventilate in the new building, or it is not possible to
14:31:440Michele De Carli: control the indoor parameters by just digest a bit and opening and closing the room.
14:43:440Michele De Carli: Okay, so
14:45:620Michele De Carli: ventilation is necessary. Okay, is treated is, let's say mandatory. Okay? Also, because if we if we ventilate, we have a better indoor air quality.
14:58:600Michele De Carli: Now, which are the possibilities to have air entering.
15:03:440Michele De Carli: opening, and closing windows is iron irration. Okay? So it's not ventilation. We cannot properly talk about ventilation. It's not natural ventilation, natural ventilation. We can do that. But in that case
15:19:772Michele De Carli: you should make anyway, a design. There are some
15:25:910Michele De Carli: specific tools which you can use, but they are complicated. Okay? So we want to look at them because
15:32:940Michele De Carli: they are. I mean.
15:35:930Michele De Carli: they are not easy to handle. You have to consider dynamic condition when the direction and so on. Let's say that you can do
15:44:800Michele De Carli: the natural ventilation. Okay? But you have to design it. Okay? So you need a design. You need to select
15:52:70Michele De Carli: okay, proper ventilation system which allow natural ventilation. Okay.
16:00:590Michele De Carli: so you can do that. But it's complicated. Okay,
16:15:160Michele De Carli: wow.
16:16:440Michele De Carli: and no, I don't want to add any more stuff from that. Then we have the mechanism called mechanical ventilation. Okay? So mechanical ventilation is actually what we can do in order to have mechanical ventilation.
16:31:450Michele De Carli: We see we need a fan. Okay, at least one fan. Okay, for driving the air okay, into or from the building towards outside. We need.
16:44:90Michele De Carli: we can have one fan or 2 funds. Okay? And of course we can have or not. That's okay to drive the into the different locations inside.
16:54:820Michele De Carli: That is mechanical integration. We can have also a mix of the natural and mechanical detonation by means of this
17:03:134Michele De Carli: so-called hybrid integration. Of course, for
17:06:245Michele De Carli: sake of time we will just look at the mechanical information. Okay? So we will see the mechanical information on how it works. Okay?
17:17:750Michele De Carli: So well, these are definition, mechanical ventilation. So for mechanical ventilation, we have a standard is the 12, 7, 9, 2, which is a product standard. Okay? And it's defining how you can ventilate a building. Okay?
17:37:429Michele De Carli: That is also the question of infiltrations. Okay? So infiltrations are, instead, the air flow rates. Okay? Which are
17:49:340Michele De Carli: entering the the building from different. Let's say, points. Okay, could be windows could be through the, for instance, the electric plants. Okay? Because we have. We have plastic pipes. Okay? And in in that case, we have some permeable
18:10:100Michele De Carli: in principle. Points. Okay?
18:13:960Michele De Carli: And we might have different infiltration points. Okay, let's say that infiltration might be a problem, especially in very cold climates. Also, in in severe climates, in very cold climates, infiltration could be a problem. Okay.
18:33:440Michele De Carli: let's say that in our, in our climate you can
18:38:710Michele De Carli: check the infiltration rate. Okay, there are some tests that you can do. Okay in order to see how tight your your envelope is. But let's say that, even though, or even if you have some infiltration. Okay, that is not a big problem. Okay, apart, if you are working with the
18:59:140Michele De Carli: some very specific okay heating system, especially for full air system for residential buildings, which is a little bit.
19:11:860Michele De Carli: they might be
19:13:700Michele De Carli: not really high oversized. Okay? So in that case, you might have problem. Okay? But I mean, apart, this type of system. Usually you don't have people. Remember.
19:24:560Michele De Carli: the air tightness is also related to the way you build the building? Okay? I mean, if you work with the usual let's say wet materials. You have less problem of tightness than if you are using dry. Okay, prefabricated materials like wooden structures. Okay? So in that case.
19:49:250Michele De Carli: you might have some infiltration. Okay, due to the to the fact that you might have some some leakages, and you have not.
19:59:710Michele De Carli: You can control that somehow. Okay. And I mean, from the let's say, energy and power point of view, it's not a very good stuff. Okay, at least in our in a cold climate. Okay, if you have minus 20 degrees as design condition, then you should consider the infiltration, because, of course, the infiltration will increase
20:21:260Michele De Carli: by the increasing of Delta T between inside and outside. I think if outside is getting cold.
20:27:970Michele De Carli: Okay, then you have a high pressure drop between our side and inside, and you get information inside of it
20:34:480Michele De Carli: gate.
20:35:470Michele De Carli: But let's say, this is not a big problem.
20:39:840Michele De Carli: Now, what about mechanical information? So we have talked about this. We have made this introduction. Now we can. We I would like to talk about the mechanical information and
20:57:272Michele De Carli: mechanical ventilation, we we can consider, let's say, 3 types of mechanical ventilation system. Okay, according to Pm. 12, 7, 9. Okay? I,
21:15:650Michele De Carli: okay, I will show you, okay, briefly, the 3 types of ventilation. And then I think we have to stop because the lecture is almost over. Okay? So the 1st type of ventilation you can see it's called balanced ventilation. Okay, it's called.
21:31:730Michele De Carli: I also named Dual flow. And what does it mean? It means that basically, you can see
21:41:313Michele De Carli: in this case we have
21:43:250Michele De Carli: a you can see there are 2 circles with the triangle which are, let's say, representing fans, of course. So we have 2 fans. So we have one fan driving the air into the building
21:58:570Michele De Carli: through these dots. Okay, through the dark. It's sorry to the through the black dots. Okay, which are the supply
22:07:410Michele De Carli: air dots. Okay, the air is blown into the different rooms. Okay?
22:14:270Michele De Carli: And then you have a exhaust or return. Let's say, return, doctor. The red one.
22:22:300Michele De Carli: Okay. Well, you see that the arrows okay are converging into this dot. Okay, so we have that
22:28:460Michele De Carli: in this case the fund is he's a
22:35:770Michele De Carli: is making a depression. Okay, this fan here is is,
22:42:610Michele De Carli: is realizing under pressure in the
22:46:580Michele De Carli: in this, that here, okay? And then it's blown away. Okay, so this is the exhaust that with the polluted
22:54:920Michele De Carli: okay and humid air and the black
22:59:989Michele De Carli: the black duct is instead, the one related to the today. And
23:06:920Michele De Carli: this one here, this one here is
23:09:580Michele De Carli: taking the air from outside. Okay? And then the air is blown inside the building. Okay?
23:18:790Michele De Carli: We
23:19:990Michele De Carli: 2 or more dots. Okay? And the air is released into the building. And then we have then one or more exhausted dots. Okay, so the the fan
23:32:170Michele De Carli: which is driving the air is
23:35:340Michele De Carli: over, pressurizing the the rooms. Okay, and the fan which is taking out, bringing the air. Let's say, okay, or pulling the air
23:51:78Michele De Carli: out is
23:54:530Michele De Carli: making the rooms into the pressure. Okay, what is important to understand is that in that case
24:01:390Michele De Carli: we have a certain well, the mass flow rate, which is the supply. Okay?
24:11:860Michele De Carli: And we have a certain flow rate exhaust or return. Okay.
24:25:860Michele De Carli: if these 2 flow rates are the same, then we have a balanced omission. Okay? So the the
24:33:130Michele De Carli: the the room is neither in pressure or in the in the pressure. Okay, if we
24:42:300Michele De Carli: have more air into the room that we supply than the air that we are extracting we are.
24:54:890Michele De Carli: We have over pressure in the rooms. Okay?
24:59:652Michele De Carli: If instead, we have, we are extracting more fluorine, more air, then we are supplying. Then we are under pressuring. Okay, we have
25:12:800Michele De Carli: the rooms which are under pressure. Okay.
25:16:970Michele De Carli: it depends what you want to do. Okay?
25:20:870Michele De Carli: So if the the rooms are critical. So I mean, if in the room you need to maintain a certain quality, and you need, for instance, you are producing, imagine that you in this room you are producing.
25:36:141Michele De Carli: I don't know a microchip, okay, or or
25:39:650Michele De Carli: or a Pv cell. Okay, then, in that case, the air that you have to provide should be here. So you will filter the air. Okay? And in that case you will make an over pressure. Okay? So you will.
25:53:480Michele De Carli: You will insert more air in the room than you will extract. But, for instance, if you have, like a covid, okay.
26:02:900Michele De Carli: area, okay, or an area where you might have some viruses. Okay, or bacteria. Okay?
26:12:40Michele De Carli: Then, in these days you will under pressure this because you don't want
26:17:00Michele De Carli: any exfiltration of a polluted air into other in the surrounding. Okay, so it depends. So this is one possibility. Okay.
26:30:40Michele De Carli: you might have also a so-called single flow. Okay, as we'll see tomorrow.
26:36:680Michele De Carli: In this case you are under pressure.
26:42:30Michele De Carli: the room. So you have just one fan. Okay, so you are extracting here. Okay?
26:49:320Michele De Carli: And of course you will.
26:52:810Michele De Carli: The air will enter somewhere. Okay, in the surrounding from the envelope. Okay?
27:00:130Michele De Carli: And in this case it's called exhaust ventilation, because you have just one fan which is exhausting the air. Okay.
27:10:550Michele De Carli: R, and this is, let's say, more
27:16:340Michele De Carli: common in in Italy, but also in France. Okay.
27:20:787Michele De Carli: R, which is more instead, the common in
27:25:720Michele De Carli: Uk, okay? You can have this so called the supply ventilation. So you have always one fan. Okay? But in this case the fan is
27:36:480Michele De Carli: pushing the air. Okay, into the rooms. And then they're actually sitting from there. So these are 2 different, let's say.
27:46:390Michele De Carli: philosophies. Okay, that you can work. Okay. So a single flow. We have just one fan, either
27:56:510Michele De Carli: for the exhaust or for the supply dual flow.
28:02:490Michele De Carli: You have 2 files, and you have
28:05:680Michele De Carli: a series of that for both the supply and the exhaust.
28:10:630Michele De Carli: Okay, okay, so I think it's enough for today.
28:17:70Michele De Carli: No, I don't think it's enough for today, because we we finish our time. Okay? And we meet again tomorrow.